Transfer roller

ABSTRACT

A transfer roller for a transfer roller assembly to be included within an electrostatographic machine wherein the transfer roller is texturized by providing a plurality of grooves and ridges having a vertical distance therebetween of from about 0.003 to 0.008 inches. The roller may include a coating of a high gloss durable material.

United States Patent n 1 Hoffman et a1.

[ 51 Mar. 5, 1974 TRANSFER ROLLER Inventors: Daniel S. Hoffman, Rochester;

Thomas Meagher, Webster; Robert J. Michatek, Fairport, all of N.Y.

Xerox Corporation, Stamford, Conn.

Filed: Aug. 9, 1972 Appl. N0.: 278,984

Assignee:

US. Cl. 355/3 R, 29/121 R, 118/637, 271/51 Int. Cl G03g 15/16 Field of Search 355/3 R, 3 DD, 16, 17; 96/1.4; 117/17.5; 118/637, DIG. I5, DIG. 24, 621; 29/121 R; 27l/DIG. 3, 63 A, 51

References Cited UNITED STATES PATENTS 1/1973 Sargis 355/3 R X 3,630,591 12/1971 Eastman 355/3 R 1,185,260 5/1916 Stine 226/177 2,153,154 4/1939 Nivison et al.. 271/8 3,697,171 10/1972 Sullivan 355/16 X 3,115,814 12/1963 Kaprelian 355/3 Primary ExaminerSamuel S. Matthews Assistant Examiner-Kenneth C. I-lutchison Attorney, Agent, or Firm-Earl T. Reichert ABSTRACT 3 Claims, 2 Drawing Figures TRANSFER ROLLER BACKGROUND OF THE INVENTION This invention relates to electrostatography, and more particularly to a novel transfer roller for an electrostatographic apparatus.

In the practice of xerography as described in US. Pat. No. 2,297,691 to Chester F. Carlson, a xerographic surface comprising a layer of photoconductive insulating material affixed to a conductive backing is used to support electrostatic images. In the usual method of carrying out the process, the xerographic plate is electrostatically charged uniformly over its surface and then exposed to a light'pattern of the image being reproduced to thereby discharge the charge in the areas where light strikes the layer. The undischarged areas of the layer thus form an electrostatic charge pattern in conformity with the configuration of the original light pattern. I I

The latent electrostatic image may then be developed by contacting it with a finely divided electrostatically attratable material, such as a resinous powder. The powder is held in the image areas by the electrostatic fields on the layer. Where the field is greatest, the greatest amount of material is deposited; and where the field is least, little or no material is deposited. Thus, a powder image is produced in conformity with the light image of the copy being reproduced. The powder is subsequently transferred to a sheet of paper or other surface and suitably affixed to thereby form a permanent print. The toner may be fixed by passing the sheet of paper or other surface including the transferred image between a heated roller and a second roller in pressure contact therewith whereby the toner becomes fused to the sheet of paper.

The image is generally transferred to an image receiving member by passing such a member between the photoconductive surface including the developed image and a transfer roller in contact therewith. In order to transfer effectively any such image with reliable throughput there is a need for uniform contact along the nip of the photoconductive surface and the transfer roller.

OBJECTS OF THE INVENTION An object of this invention is to provide a novel transfer roller.

Another object of this invention is to provide a novel transfer roller assembly including a transfer roller whereby wrapping of image receiving members are minimized.

SUMMARY OF THE INVENTION These and other objects of the-invention are obtained by providing a transfer roller having a texturized surface formed of a plurality of ridges and grooves. The transfer roller is provided in a transfer roller assembly rotatably supported within the housing of an electrostatographic machine in juxtaposition to a photoconductive surface therefor, such as described in copending application Ser. No. 214,289, filed Dec. 12, 1971 entitled Transfer Roller Assembly, assigned to the Xerox Corporation. Therein, the transfer roller assembly is provided with bracket means which engage spring loaded lever elements rotatably mounted on a locking shaft mounted for rotation in the housing of the machine. The locking shaft is provided with a handle for moving the shaft to an image transfer mode with the concomittant nominal rotation of the transfer roller assembly thereby bringing the transfer roller into uniform contact with the photoconductive surface.

DESCRIPTION OF THE DRAWINGS A better understanding of the present invention as well as other objects and further features thereof will become apparent upon consideration of the following detailed disclosure thereof, especially when taken with the accompanying drawings, wherein like numerals designate like parts throughout.

FIG. l is a schematic sectional view of an electrostatic reproduction machine embodying the principles of the invention; and

FIG. 2 is a partial enlarged, elevational view of the transfer roller of the invention.

For a general understanding of the illustrated copier/reproduction machine in which the invention may be incorporated, reference is had to FIG. 1 in which the various system components for the machine are schematically illustrated.

A document to be copied is placed upon a transparent support platen P fixedly arranged in an illumination assembly, generally indicated by the reference numeral 10, positioned at the left end of the machine.

Light rays from the illumination system are flashed upon the document to produce image rays corresponding to the informational areas. The image rays are projected by means of an optical system onto the photosensitive surface ofa xerographic plate in the form of a flexible photoconductive belt 12 arranged on a belt assembly, generally indicated by the reference numeral The belt 12 comprises a photoconductive layer of selenium which is the light receiving surface and imaging medium for the apparatus, on a conductive backing. The surface of the photoconductive belt is made photosensitive by a previous step of uniformly charging the same by means of a corona generating device or corotron 13.

The belt is journaled for continuous movement upon three rollers 20, 21 and 22 positioned with their axes in parallel. The photoconductive belt assembly 14 is slidably mounted upon two support shafts 23 and 24 with the roller 22 rotatably supported on the shaft 23 which is secured to the frame of the apparatus and is rotatably driven by a suitable motor and drive assembly (not shown) in the direction of the arrow at a constant rate. During exposure of the belt-l2, the portion exposed is that portion of the belt running between rollers 20 and 21. During such movement of the belt 12, the reflected light image of such original document positioned on the platen is flashed on the surface of the belt to produce an electrostatic latent image thereon at exposure station A.

Y As the belt surface continues its movement, the electrostatic image passes through a developing station B in which there is positioned a developer assembly generally indicated by the reference numeral 15, and which provides development of the electrostatic image by means of multiple brushes 16 as the same moves through the development zone.

The developed electrostatic image is transported by the belt to a transfer station C wherein the present invention is'positioned and whereat a sheet of copy paper is moved between a transfer roller and the belt at a speed in synchronism with the moving belt in order to accomplish transfer of the developed image solely by an electrical bias on the transfer roller. There is provided at this station a sheet transport mechanism generally indicated at 17 adapted to transport sheets of paper from a paper handling mechanism generally indicated by the reference numeral 18 to the developed image on the belt at the station C.

After the sheet is stripped from the belt 12, it is conveyed into a fuser assembly, generally indicated by the reference numeral 19, wherein the developed and transferred xerographic powder image on the sheet material is permanently affixed thereto. After fusing, the finished copy is discharged from the apparatus at a suitable point for collection externally of the apparatus.

Further details regarding the structure of the belt assembly 14 and its relationship with the machine and support therefor may be found in the copending Application Ser. No. 102,312, now US. Pat. No. 3,730,623, assigned to the same assignee.

Referring now to FIG. 2, there is illustrated a texturized transfer roller, generally indicated as 30, formed of a plurality of grooves 32 and ridges 34 having a vertical distance therebetween of from 0.003 to 0.008 inches. To form the transfer roller of this invention, a knurled surface is provided on the internal surface of a cylindrically-shaped mold having an internal diameter equal to the desired diameter of the transfer roller. The knurled surface is formed utilizing standard knurling techniques as is known to the one skilled in the art to form, for example, a 30 diamond pattern. A plastic material such as an urethane, having suitable electrical and physical properties, i.e., resistivity (about 4 X and flexibility, is introduced into the mold and subjected to standard plastic molding techniques. After cooling, the center is bored to permit the insertion of a metallic shaft 36. Alternately, the shaft 36 may be positioned within the mold prior to the introduction of the plastic material.

In a particularly preferred form of the invention, a transfer roller is formed with about 50 grooves per inch and having a vertical distance between the grooves and ridges of from about 0.005 to 0.010 inches, which roller is thereafter coated (about 0.002 inches) with a high gloss durable material, such as ADIPRENE (a registered trademark of duPont) to provide a coated transfer roller having grooves and ridges with a vertical distance therebetweenv of from about 0.003 to 0.008

inches. The coating material facilitates removal of toner from the transfer roller. While discussed with reference to a knurled surface of standard configuration, the angle and the lines per inch of the grooves and ridges may be varied provided the texturized surface is provided with grooves and ridges having a vertical distance therebetween of about 0.003 to 0.008 inches. Too small a depth results in a too frequent wrapping of image receiving members about the transfer roller while too great'a depth results in the print-out" of such texturized surface on the image receiving members.

Other modifications of the present invention will occur to those skilled in the art upon a reading of the present disclosure which modifications are intended to be included within the scope of this invention.

What is claimed is: V

1. In a reproduction machine includingmeans for providing a developed, electrostatic image on a member and means for passing sheets of support material 'seriatim into contact with said member for transfer of the developed image from said member to the support material, the improvement comprising;

a transfer roller mounted for rotation in contact with said member for passage of the support material therebetween to transfer the developed image from said member to the support material, said transfer roller being provided with a plurality of grooves and ridges having a vertical distance therebetween of from 0.003 to 0.008 inches.

2. A reproduction machine according to claim 1 wherein said transfer roller includes a coating of a high gloss durable material.

3. A reproduction machine comprising;

a member,

means for forming -a developed electrostatic on said member,

transfer means adapted for contact with. said member,

means for feeding sheets of support material between image said member and said transfer means for transferring the developed electrostatic image from said member to the support material, the'surface of said transfer means having a plurality of grooves and 

1. In a reproduction machine including means for providing a developed, electrostatic image on a member and means for passing sheets of support material seriatim into contact with said member for transfer of the developed image from said member to the support material, the improvement comprising; a transfer roller mounted for rotation in contact with said member for passage of the support material therebetween to transfer the developed image from said member to the support material, said transfer roller being provided with a plurality of grooves and ridges having a vertical distance therebetween of from 0.003 to 0.008 inches.
 2. A reproduction machine according to claim 1 wherein said transfer roller includes a coating of a high gloss durable material.
 3. A reproduction machine comprising; a member, means for forming a developed electrostatic image on said member, transfer means adapted for contact with said member, means for feeding sheets of support material between said meMber and said transfer means for transferring the developed electrostatic image from said member to the support material, the surface of said transfer means having a plurality of grooves and ridges formed therein, said grooves and ridges having a vertical distance therebetween of from 0.003 to 0.008 inches. 